What is the rate of discount on a dvd player having a marked price of $240 but sold for $216?

In order to find out the discount of a product, it's usually the price reduced divided by the original price and then calculate the decimal to the percent then minus it from 100% to find out what percentage has been taken off.

So for this problem, it's $216/$240 = 0.9 = 90% 
100% - 90% = 10% 
($240 * 0.1 = $24, $240 - $24 = $216)

In conclusion, the original price has been reduced 10%

Iwould think that the correct answer is 8.1